1. Field
The present disclosure relates to a method, system, and an article of manufacture for maintaining consistency for asynchronous remote copy using virtualization.
2. Description of the Related Art
Information technology systems, including storage systems, may need protection from site disasters or outages. Furthermore, information technology systems may require features for data migration, data backup, or data duplication. Implementations for disaster or outage recovery, data migration, data backup, and data duplication may include mirroring or copying of data in storage systems. In certain information technology system, data is copied from a primary storage control to a secondary storage control. In response to the primary storage control being unavailable, the secondary storage control may be used to substitute the unavailable primary storage control.
Data copying in information technology systems may be synchronous or asynchronous. Synchronous copying involves sending data from the primary storage control to the secondary storage control and confirming the reception of such data before completing write operations to the primary storage control. Synchronous copy, therefore, slows the write operation response time while waiting for the confirmation from the secondary storage control. Synchronous copy, however, provides sequentially consistent data at the secondary storage control.
Asynchronous copy may provides better performance than synchronous copy because the write operation to the primary storage control may be completed before the reception of sent data is confirmed from the secondary storage control. However, data sequence consistency may have to be ensured since data received at the secondary storage control may not be in order of the updates, i.e., write operations, to the primary storage control. In asynchronous copy, cross-device consistency between the primary and the secondary storage control may be achieved by storing updates temporarily in a hardened location, such as a journal dataset, until a set of consistent updates is available to apply to the secondary storage associated with the secondary storage control.